1. Field of the Invention
The present invention relates to power take-off mechanism for a primary internal combustion engine of a vehicle. More specifically, the present invention relates to mechanism for coupling a hydraulic pump to the front or nondriving end of a marine engine crankshaft and enabling the pump to be spaced radially from the crankshaft without applying appreciable radial force to the crankshaft.
2. Prior Art
A variety of hydraulically powered add-on accessories have been proposed for large boats and yachts, such as hydraulically powered bow thrusters. Such accessories require a high capacity pump. It is desirable to drive such a pump by the existing internal combustion engine, as compared to providing a separate source of power for driving the pump, but coupling a high capacity pump to an existing engine has presented several problems. If the pump is to be coupled to the rear or driving end portion of the engine crankshaft, there may be no convenient location for mounting the pump and major alterations to the drive shaft and couplings may be required. If the pump is to be coupled to the front or nondriving end portion of the crankshaft, again there may be no conveniently accessible location for the pump. In either event, the crankshaft and its supporting bearings cannot withstand substantial radially directed force such as would result if the high capacity pump is simply mounted in the boat independently of the engine and coupled to the crankshaft by pulleys and a belt. The minimum disadvantage of such an installation would be voiding the manufacturer's warranty for the engine.
It has been proposed to mount the pump in front of an engine with the pump input shaft coaxial with the engine crankshaft. Such a coaxial installation may require more space than is available in front of an existing engine.
Another problem is that the engine vibrates, twists in response to the output torque and even surges fore-and-aft in response to the developed thrust. When a hydraulic pump is mounted separately from the engine, such movement of the engine increases wear and tear on the couplings and bearings.
Hamm U.S. Pat. No. 4,406,633, issued Sept. 27, 1983, discloses a marine engine power take-off for a hydraulic pump in which the pump is mounted on the keel separately from the primary engine and is coupled to the rearward-projecting end portion of the crankshaft.
Krautkremer U.S. Pat. No. 4,175,511, issued Nov. 27, 1979, discloses a tugboat having hydraulically powered thrusters with the hydraulic pump being coupled to the front or nondriving end of an engine crankshaft.
Brown et al. U.S. Pat. No. 4,300,872 discloses a system for mounting a hydraulic pump on an outboard motor with the pump input shaft coaxial with the flywheel.
Holmes U.S. Pat. No. 3,756,751 discloses a hydraulic pump mounted on the clutch housing of a forklift truck and driven by the lift truck engine.